/***************************************************************************
    copyright            : (C) 2003 by Michael Speck
    email                : http://lgames.sf.net
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef PARTICLE_H
#define PARTICLE_H

#include "defs.h"

enum {
	PT_SMOKE = 0,	/* animate if frame_change is set and fade out by modifying the
			   alpha by alpha_change*ms. remove the particle when it becomes
			   invisible. uses wind vector. */
	PT_EXPLOSION, 	/* animate through all frames with defined alpha but do not change it. 
			   wind and gravity do not have influence. when animation is finished 
			   type is set to smoke and set direction vector to a very slow random
			   movement. */
	PT_FIRE,	/* first part as PT_EXPLOSION except that wind has always influence.
			   when animation is done type is set to PT_SMOKE but the direction
			   vector is not changed */
	PT_BALLISTIC,	/* move particle under influence of wind and gravity and remove
			   it when the particle has reached the ground again (pos.z==0).
			   if alpha_change is set the particle is removed when invisible. */
	PT_WASTE	/* inanimate/unmoved particles that fade away */
};

typedef struct {
	int		type;		/* type of particle */
	SDL_Surface	*img;		/* resource image */
	int		img_x_offset;	
	int		img_y_offset;	/* image may contain different particles */
	int		w, h;		/* size of the particle */
	double		frame; 		/* if particle is animated, this is the floating point
					   frame id to apply frame_change correctly */
	int		frame_id;	/* the integer frame_id (int)frame used to display the 
					   current frame */
	double		frame_change;	/* change in frame / ms */
	double		frame_count;	/* number of frames in the horizontal strip. it is of
					   type double to save a type conversion when checking this */
	double		alpha;		/* alpha of particle. the old alpha of image is not
					   restored */
	double		alpha_change;	/* change of alpha / ms */
	Vector		pos;		/* coordinates of the particle */
	Vector		dir;		/* direction particle is moving to: 
					   change of coordinates / ms */
	Vector		*wind;		/* the wind vector (direction change/ms) is used to modify 
					   the direction. it is assumed that w == h (at least it
					   should not differ too much) and the effect of wind is
					   proportional to the particle's width (representing mass) */
	Vector		*grav;  	/* gravity vector (direction change/ms). both vectors do only 
					   have effect when the particle's type require them and they 
					   are not NULL. */
} Particle;

typedef struct {
	int	type;		/* smoke or fire */
	int	x,y;		/* coordinates */
	int	radius;		/* radius of emitting area */
	int	lifespan;	/* time in ms emitter will be active */
	double	rate;		/* particles / ms */
	double	count;		/* number of particles to be emitted next */
} Emitter;

void particles_draw( SDL_Surface *dest, int camera_x, int camera_y );

void particles_update( int ms );

void particles_add_emitter( int type, int x, int y, int radius, double rate, int lifespan );

void particles_clear(); /* clear emitters and particle */

/* customized particle creation */

void particles_set_fire( int x, int y, int radius, int density );

void particles_set_smoke( int x, int y, int radius, int density );

void particles_set_muzzle_fire( int x, int y, int density );

void particles_explode_human( int x, int y, int sx, int sy );

void particles_explode_bomb( int x, int y );

void particles_explode_grenade( int x, int y );

void particles_explode_clusterbomb( int x, int y );

#endif